Iodine is a very important trace element necessary in the biosynthesis of thyroid hormones. On the other hand, deficiency of iron leads to anemia. Deficiencies of iron and iodine severely affect more than a third of the world's population.
Recognizing that salt is consumed in similar amounts by rich and poor alike, salt is considered to be an excellent vehicle to deliver the body's requirement of iodine and iron.
Reference may be made to the first revision of IS 12981:1991 pertaining to iron fortified iodized salt (double fortified salt) food grade specification wherein it is indicated that the specified ranges of iodine and iron are 30 ppm (min) at manufacturer's level and 850-1100 ppm, respectively.
Reference may be made to the same IS 12981:1991 wherein it is stated that the colour of the salt may be white or pink or grey.
Reference may be made to the same IS 12981:1991 wherein no information is given of stability of iron and iodine in the product nor any justification as to why 1% sodium hexametaphosphate should be a mandatory specification in double fortified salt.
Reference may again be made to the same IS 12981:1991 wherein it is stated that the purity of the NaCl used must be >99% whereas it is well known that edible salt consumed by the masses can have purity anywhere in the range of 96-99%.
Reference may be made to an article by B. S. Narsinga Rao, available at www.unu.edu/unupress/food/8F15le/8F151F06.htm entitled “Fortification of salt with iron and iodine to control anemia and goiter: Development of new formula with good stability and bioavailability of iron and iodine” wherein the author has prepared double fortified salt by mixing thoroughly ferrous sulphate, potassium iodide or iodate and stabilizers such as sodium hexa meta phosphate to the optimized content of 1%, The iodine loss was measured from initial of 20 μg/gm to 12 μg/gm within storage of 3 months period when iodine was added as KIO3. Thus the product appears to not have the requisite stability.
Reference may be made to a paper entitled “Micro encapsulation for iodine stability in salt fortified with ferrous fumarate and potassium iodide” by Diosady L. L. et. al., in Food Research International, 2002, Volume 35, Issue 7, pp 635-642 wherein potassium iodide or potassium iodate was encapsulated in modified starches, gelatin, sodium hexametaphosphate and purified sodium chloride by spray drying and fluidized bed drying to produce microcapsules containing 0.3 to 2% iodine. The encapsulation is to provide physical barrier to iodine compound and employs expensive and cumbersome method of spray drying. Moreover, the ferrous fumarate used has unpleasant brown color which mars the aesthetic appearance of double fortified salt so prepared.
Reference may be made to a paper entitled “Dual fortification of salt with iodine and micronized Ferric pyrophosphate: a randomized, double-blind, controlled trial “by M. B. Zimmermann et al in Am. J. Clin. Nutr 80,952-959, 2004, wherein they have used DFS containing iodine and micronized ferric pyrophosphate as an effective fortification strategy in rural Africa. The stability has been reported to be 6 months.
Reference may be made to a paper entitled “A study of storage and distribution of double fortified salts in Kenya” by L Diosady et al Journal of Food Engineering, Volume 76, Issue 4, October 2006, 547-556, wherein Twenty-one formulations of double fortified salts were prepared by either blending the different iron premixes with either iodated salt, or iodine premix and blank salt. All the microencapsulated double fortified salt formulations retained most of the ferrous iron and iodine during the three-month study period. However, the results showed that double fortified salt (DFS) prepared with ferrous fumarate as the source of iron was generally more stable than those prepared with the other iron premixes investigated under typical environmental conditions of the salt distribution networks in Kenya. For DFS with ferrous fumarate premix and potassium iodide premix, the average iodine and ferrous iron retention obtained were 92% and 90%, respectively, for the Coastal (Mombasa) Zone, while for the Highland (Nairobi) Zone the average iodine and iron retentions were 87% and 86%, respectively. However they obtained good stability of iodine and ferrous using KI and Ferrous fumarate for three month only.
Reference may be made to U.S. Pat. No. 699,814 by Nestec SA, wherein a ferric fortification system is used for iron fortification of food stuff and beverages. A complex is formed using ferric compound and caseinate for its application and found to be stable and bioavailable. There is no mention of its utility for formulation of double fortified salt.
Reference may be made to PCT publication WO 2009/074998 A2, wherein use of ferrous ammonium phosphate as iron fortifying agent with iodized salt to prepare double fortified salt is disclosed. The stability of iodine and iron is ascribed to chelating form of iron. The main drawback of the patent is that the stability of iodine was measured over a period of only sixty days. Moreover, use of ammonium containing ferrous compound is undesirable.
Reference may be made to U.S. Pat. No. 4,629,626, which discloses the preparation of hydrotalcite like structure wherein Mg2+ in the conventional hydrotalcite structure is replaced with Fe2+ ion. The main drawback of the invention is that the compound so prepared is greenish in color and gets converted into brown color on exposure to air.
Reference may be made to a paper entitled “Iron-Magnesium Hydroxycarbonate (Fermagate): A Novel Non-Calcium-Containing Phosphate Binder for the Treatment of Hyperphosphatemia in Chronic Hemodialysis Patients” by Christopher W. McIntyre et al in Clin J Am Soc Nephrol 4: 401-409, 2009, wherein it is disclosed that Fermagate (Ineos Healthcare, Warrington, United Kingdom) contains magnesium and ferric iron held in an insoluble hydrotalcite structure [Mg4Fe2(OH)12]2+.CO32−.mH2O]. The iron and magnesium are held in a tight crystalline-layered structure, with carbonate groups, which are exchanged for phosphate, lying between the layers. The product is indicated to be coloured.
Reference may be made to a paper entitled “A study of phosphate absorption by magnesium iron hydroxycarbonate” by Yi Du, Nicholas Rees and Dermot O'Hare, in Dalton Trans., 2009, 8197-8202 wherein description is given for the synthesis of hydrotalcite structure containing iron and magnesium. The main drawback of this iron containing Fe3+ is that it is made using nitrate salt that results in nitrate containing effluent and the obtained product was orange yellow in color.
Reference may be made to U.S. Pat. No. 7,695,707 dated 13 Apr. 2010, entitled “An improved iodized salt and a process for its preparation” by P. K. Ghosh et al assigned to CSIR, which discloses a method for preparation of iodizing agent for the use in the formulation of iodized salt that offers excellent stability of iodine in iodized salt.
Reference may be made to South African patent ZA200004598 (A) or its equivalent Indian Patent No. 193455 assigned to Unilever which discloses a food component, particularly iodine fortified sodium chloride and a process for obtaining iodine intercalated in the interlayer spaces of layered double hydroxide.
Reference may be made to US patent Application Publication No. US 2010/0203152, wherein use of Mg, Fe hydrotalcite like crystal structure has been described as antacid.
Reference may be made to the paper by S. Piomelli et al. (Blood, 1973, 41, 451) wherein it is reported that not only iron deficiency but deficiency of magnesium too can lead to anaemic conditions.
Reference may be made to the review paper entitled “Magnesium deficiency and diabetes mellitus” by Chetan P. Hans, in Current Science, Vol. 83, No. 12, 25 Dec. 2002, wherein the functional role of magnesium in the pathogenesis of diabetes is described and introduces a relatively new concept on the implication of magnesium deficiency in diabetic complications.
It would be evident from the prior art that iron, magnesium and iodine are all useful micronutrients for the body and there is no report of any product of the three together which has white colour and long stability.